This invention relates generally to tacky polymeric microspheres, and has particular reference to inherently tacky, elastomeric, solvent-dispersible, solvent-insoluble, polymeric microspheres and a process for preparing same using a non-ionic emulsifier.
In U.S. Pat. No. 4,166,152, granted Aug. 28, 1979 to W. A. Baker et al, there is a disclosure of inherently tacky acrylate homopolymer microspheres prepared by aqueous suspension polymerization techniques utilizing a suspension stabilizer and an anionic emulsifier. The microspheres prepared by this method had an average particle size of 10-60 microns. While the inherently tacky microspheres disclosed by Baker have desirable properties for certain applications, it has been found that anionic emulsifiers retard particle coalescence by surrounding the particle with a charged double layer. This coulombic barrier of the anionic emulsifiers is sensitive to electrolytes and freezing, and sensitivity to freezing can be a disadvantage in cold weather shipments and during storage.
Other pertinent prior patents of which the applicant is aware are U.S. Pat. Nos. 3,513,120; 3,691,140; 3,857,731; 4,049,483 and 4,049,604.